Because of rapidly dwindling petroleum reserves, coal has evidenced increasing importance as a source of fuel. Many processes have been developed to utilize coal directly in solid form by combustion, or by first converting it to useful liquids and gases. However, many of these processes suffer because of problems associated with the mineral matter contained in coal. For example, mineral matter in coal can cause recycle problems in liquefaction processes by causing the loss of hydrogen to form the undesirable side product H.sub.2 S. Mineral matter can also be a problem if the coal is burned directly because mineral matter contributes to slagging problems. Mineral matter in coal will also contribute to the release of sulfur dioxide as a pollutant. Therefore, it is highly desirable to remove as much of the mineral matter as possible before coal utilization.
Although various methods have been proposed for the removal of mineral matter from coal, there is still a need in the art for the development of more efficient and effective demineralization methods, especially if chemical comminution of the coal can be simultaneously achieved.